This invention relates to a surface water outlet device of the type used to allow water to be drained from sediment ponds or basins, in order to prevent overflow and flooding of surrounding areas. These devices are sometimes referred to as “skimmers.” Sediment ponds are frequently used to prevent or minimize water runoff from agricultural land and construction sites where rain or other water sources may erode and wash large amounts of sediment onto roads, yards and other areas if not controlled. Sediment has a particularly detrimental effect on drinking water supplies and can substantially reduce the volume of water that can be stored in rivers and impoundments used to supply municipal water systems.
Sediment ponds are constructed according to regulations, and typically include temporary soil embankments raised above the surrounding land forming the impoundment, a filter fabric bottom liner, a series of vertical baffle and an inflow structure such as one or more pipes that allows surface and drainage water to flow into the pond. An emergency spillway somewhat below the level of the top of the embankment allows water to flow out through the spillway instead of overtopping and eroding the embankment.
Regulations now require sediment ponds to be equipped with a flotation device that drains water from the pond at a controlled rate when the water reaches a specified level. The device is intended to drain water from the very top surface at a controlled rate, resulting in the clearest possible discharge, while the sediment remains on the bottom of the pond or basin.
The present invention solves several existing problems in the operation of prior art outlet devices by permitting a single device that can be field adjusted and used on a wide range of basin volumes by allowing variable discharge flow based on water depth that insures proper water retention times during rain events of any size.